Contents
- Weather in September
- Frequently asked questions
- Average temperature in September
- Average pressure in September
- Average wind speed in September
- Average humidity in September
- Average rainfall in September
- Average rainfall days in September
- Average snowfall in September
- Average snowfall days in September
- Average daylight in September
- Average sunshine in September
- Average sunshine days in September
- Average UV index in September
- Average cloud cover in September
- Average visibility in September
Weather in September
Temperature
As August transitions into September, Sammamish sees a gentle drop in the average high-temperature, transitioning from a warm 76.5°F (24.7°C) to a pleasant 69.8°F (21°C). Sammamish records a steady low-temperature average of 48.9°F (9.4°C) during September.Humidity
The average relative humidity in September is 75%.Rainfall
In September, the rain falls for 10.1 days. Throughout September, 1.06" (27mm) of precipitation is accumulated. In Sammamish, during the entire year, the rain falls for 136.7 days and collects up to 13.39" (340mm) of precipitation.Snowfall
In Sammamish, snow does not fall in May through October.Daylight
In Sammamish, the average length of the day in September is 12h and 33min.On the first day of September, sunrise is at 6:27 am and sunset at 7:47 pm. On the last day of the month, sunrise is at 7:07 am and sunset at 6:48 pm PDT.
Sunshine
The average sunshine in September is 9.2h.UV index
The average daily maximum UV index in September is 3. A UV Index reading of 3 to 5 represents a medium health hazard from exposure to the Sun's UV rays for ordinary individuals.Note: In September, a daily UV index of 3 turns into the following recommendations:
Prioritize safety - The need to safeguard skin and eyes from harm is emphasized. Midday is when the Sun's radiation is strongest; avoid prolonged exposure during this time. For holistic sun protection encompassing the eyes, ears, face, and neck, a wide-brim hat is key. Be on the lookout! Nearly twofold UV radiation from the Sun can be reflected by snow.
Published by: Weather U.S. | About Us
Data Sources | Weather Forecasting & Climate
Frequently asked questions
What is the average September temperature?
What is the average humidity in September?
How much does it rain in September?
When it does not snow?
What is the average length of the day in September?
When are sunrise and sunset in September?
How long on average sun shines in September?
What is the UV index intensity in September in Sammamish?
Average temperature in September
Sammamish, WA
- Average high temperature in September: 69.8°F
The warmest month (with the highest average high temperature) is August (76.5°F).
The month with the lowest average high temperature is December (42.3°F).
- Average low temperature in September: 48.9°F
The month with the highest average low temperature is August (52.2°F).
The coldest month (with the lowest average low temperature) is December (33.6°F).
Average pressure in September
Sammamish, WA
- Average pressure in September: 30.01"Hg
The month with the highest atmospheric pressure is January (30.1"Hg).
The month with the lowest atmospheric pressure is August (30"Hg).
Average wind speed in September
Sammamish, WA
- Average wind speed in September: 3.7mph
The windiest month (with the highest average wind speed) is January (5mph).
The calmest month (with the lowest average wind speed) is August (3.4mph).
Average humidity in September
Sammamish, WA
- Average humidity in September: 75%
The months with the highest relative humidity are January, February and December (85%).
The month with the lowest relative humidity is July (70%).
Average rainfall in September
Sammamish, WA
- Average rainfall in September: 1.06"
The wettest month (with the highest rainfall) is December (1.85").
The driest months (with the least rainfall) are July and August (0.35").
Average rainfall days in September
Sammamish, WA
- Average rainfall days in September: 10.1 days
The month with the highest number of rainy days is March (14.8 days).
The month with the least rainy days is August (5.2 days).
Average snowfall in September
Sammamish, WA
- Average snowfall in September: 0"
The month with the highest snowfall is February (1.38").
The months with the least snowfall are May, June, July, August, September and October (0").
Average snowfall days in September
Sammamish, WA
- Average snowfall days in September: 0.1 days
The month with the highest number of snowfall days is February (3.2 days).
The months with the least snowfall days are May, June, July, August and October (0 days).
Average daylight in September /
Average sunshine in September
Sammamish, WA
- Average daylight in September: 12h and 3min
The month with the longest days is June (Average daylight: 15h and 54min).
The month with the shortest days is December (Average daylight: 8h and 30min).
- Average sunshine in September: 9h and 1min
The month with the most sunshine is August (Average sunshine: 10h and 42min).
The months with the least sunshine are January and December (Average sunshine: 4h and 12min).
Average sunshine days in September
Sammamish, WA
- Average sunshine days in September: 17.7 days
The month with the most sunshine days is August (24 days).
The month with the least sunshine days is November (13.5 days).
Average UV index in September
Sammamish, WA
- Average UV index in September: 3
The months with the highest UV index are June and July (UV index 5).
The months with the lowest UV index are January, February, November and December (UV index 2).
Average cloud cover in September
Sammamish, WA
- Average cloud cover in September: 34
The month with the most cloud cover is December (Cloud cover 57).
The month with the least cloud cover is August (Cloud cover 26).
Average visibility in September
Sammamish, WA
- Average visibility in September: 6mi
The months with the highest visibility are June, July, August and September (6mi).
The months with the lowest visibility are January, February, March, April, May, October, November and December (5mi).
Sammamish, Washington, USA
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